Ethylene amines are used, inter alia, as solvents, stabilizers, for the synthesis of chelating agents, synthetic resins, drugs, inhibitors and surface-active substances.
Diethylenetriamine(bis(2-aminoethyl)amine; DETA), in particular, is used as solvent for dyes and is a starting material for the production of ion exchangers, pesticides, antioxidants, corrosion inhibitors, complexing agents, textile assistants and absorbents for (acidic) gases.
Numerous processes for preparing ethylene amines are described in the literature.
According to PEP Report No. 138, “Alkyl Amines”, SRI International, 03/1981, in particular pages 7, 8, 13-16, 43-107, 113, 117, the reaction of dichloroethane with ammonia at a molar ratio of 1:15 gives diethylenetriamine (DETA) in a proportion of greater than 20% by weight based on the ethylene amines formed. However, 40% by weight of higher ethylene amines are formed in addition to 40% by weight of ethylenediamine (EDA).
The formation of these higher ethylene amines (i.e. ethylene amines having a boiling point above that of triethylenetetramine (TETA)) can be substantially suppressed in favor of ethylene diamine by amination of monoethanolamine (MEOA) with ammonia (cf., for example, the abovementioned PEP Report, U.S. Pat. No. 4,014,933 (BASF AG)). However, aminoethylethanolamine (AEEA) and piperazine (PIP) are formed as by-products in this reaction.
Ind. Eng. Chem. Prod. Res. Dev. 1981, 20, pages 399-407, (C. M. Barnes et al.) describes the ammonolysis of MEOA to EDA over nickel catalysts on a mixed SiO2—Al2O3 support. Addition of water and the powdered catalyst is said to be advantageous in increasing the yield of EDA.
Disadvantages of these technologies involving suspension catalysis result, inter alia, from the need to separate the catalyst from the product. In addition, the selectivities, e.g. for the formation of DETA, are in need of improvement.
WO-A-05/014523 (BASF AG) relates to a process for preparing ethylene amines (e.g. DETA) by reaction of monoethanolamine (MEOA) with ammonia in the presence of a catalyst in a reactor (1) and fractionation of the resulting reaction product mixture, with ethylenediamine (EDA) obtained in the fractionation being reacted in a separate reactor (2) in the presence of a catalyst to form diethylenetriamine (DETA) and the resulting reaction product mixture being fed to the fractionation of the reaction product mixture resulting from reactor 1.
The earlier German patent application No. 102005019373.0 of Apr. 26, 2005 (BASF AG) relates to a process for preparing ethylene amines in which ethylene oxide is reacted continuously with ammonia under water-free conditions over an inorganic ion exchanger in a first reaction step to give a reaction product comprising monoethanolamine diethanolamine and triethanolamine in a particular weight ratio and the reaction product is subsequently reacted continuously with ammonia in the presence of hydrogen and a hydrogenation catalyst in a second reaction step.
A parallel German patent application filed on the same date (BASF AG) relates to a process for preparing ethylene amines by reaction of ethylenediamine (EDA) in the presence of specific shaped heterogeneous catalyst bodies.
A parallel German patent application filed on the same date (BASF AG) relates to a process for preparing aminodiglycol (ADG) and morpholine by reacting diethylene glycol (DEG) with ammonia in the presence of specific shaped heterogeneous catalyst bodies.